1. Field of the Invention
This invention relates generally to communications apparatus and, in particular, to a digital interface circuit between an encryption device using a serial input/output protocol and a logic device using a parallel input/output protocol.
2. Description of the Prior Art
The military currently uses a mobile sea range instrumentation system for communications and the transfer of data during the testing of weapons systems, ships, aircraft and the like. As is best illustrated in FIG. 1 the prior art mobile sea range instrumentation system comprised an antenna for transmitting and receiving data in the radio frequency range. Electrically coupled to the antenna is a relay/responder/reporter (R.sup.3) which converts the data transmitted or received by the antenna to or from a digital format. The prior art mobile sea range also includes a digital processing unit which provides digital data to or receives digital data from the R.sup.3.
There is, however, an undeniable limitation in the prior art system illustrated in FIG. 1 in that data transmitted between, for example, a ship and an aircraft during the testing of a weapons system may be of a sensitive nature or may even be classified. This, in turn, requires encryption of the data during transmission and decryption for processing by the digital processing unit. An encrypting device may be used to encrypt the data, however encrypting devices generally transmit data serially while the R.sup.3 and digital processing unit transmit parallel bytes of data.
With the disadvantages inherent in the prior art mobile sea range of FIG. 1, that is the transmission and possible compromise of sensitive or classified information, the present invention was conceived and one of its objects is to provide a means for interfacing a first logic device which utilizes a serial input/output protocol with a second logic device which utilizes a parallel input/output protocol.
It is another object of the present invention to provide a means whereby unencrypted digital data to or from a logic device which utilizes a parallel input/output protocol may be converted to a serial input/output protocol employed by an encryption unit for encryption by an encryption unit.
It is yet another object of the present invention to provide a means whereby encrypted digital data provided to or from a logic device which utilizes a parallel input/output protocol may be converted to a serial input/output protocol for unencryption by an encryption unit.
Various other advantages and objects of the present invention will become apparent to those skilled in the art as a more detailed description of the invention is set forth below.